A case report on rare occurrence of periosteal ganglion cyst in femoral intercondylar region

Abstract

Ganglions are the cysts derived from myxomatous degeneration of periarticular tissue, commonly found around wrist and foot. Ganglion cysts are uncommon in Knee region and if present their occurrence is mostly incidental and benign. Based on their location, this could be extraarticular or intraarticular. Lesions with similar pathology in subchondral region around joints are lesser common entity called Intraosseous ganglions. Rarer still is the lesion produced by myxomatous degeneration of periosteum of long bone, called periosteal ganglion. We here present a case of 35 year old Male with gradual onset, poorly localised pain behind left knee which was radiologically suggestive of periosteal ganglion, eroding the posterior aspect of femur and confirmed histopathologically following the excision of a lesion from posterior aspect of femoral condyles.

Keywords: Benign cysts around knee; Intercondylar cyst; Periosteal ganglion.

Fig. 1

Plain radiograph showing little soft tissue shadow on posterior aspect of femoral condyle.

Fig. 2

MRI Images: T1 and T2 images showing sagittal section of knee with hyperintense lesion on posterior femoral condyle above gastrocnemius origin.

Fig. 3

MRI Images: T1 and Fat-Suppressed images showing transverse section of knee with hyperintense lesion on posterior femoral condyle. This image shows vicinity of lesion with major vessels.

Fig. 4

MRI Images: Fat suppressed sagittal section of knee showing multiloculated nature of lesion and no continuation with joint.

Fig. 5

Posterior approach to knee taken with midline S shaped incision on posterior aspect of knee.

Fig. 6

Retraction of surrounding tissues to make visible the underlying periosteal ganglion.

Fig. 7

Completely excised ganglion cyst measuring 25 mm × 19 mm.

Fig. 8

Histopathology showing pseudosynovial cells arranged in cuboidal pattern enclosing gelatinous mucin.